Le 17-juin-05, à 07:19, Russell Standish a écrit :
> Hmm - this is really a definition of a universal machine. That such a
> machine exists is a theorem. Neither depend on the Church-Turing
> thesis, which says that any "effective" computation can be done using
> a Turing machine (or recursive function, or equivalent). Of course the
> latter statement can be considered a definition, or a formalisation,
> of the term "effective computation.
Hmm - I disagree. Once you give a definition of what a turing machine
is, or of what a program fortran is, then it is a theorem that
universal turing machine exists and that universal fortran program
exists. To say that a universal machine exists, computing by definition
*all* computable function, without any "turing" or "fortran"
qualification, you need Church thesis.
Bruno
http://iridia.ulb.ac.be/~marchal/
Received on Mon Jun 20 2005 - 05:41:02 PDT